Heparin is known to inhibit smooth muscle growth in culture and in vivo following experimental carotid injury. Because in many cases cells increase in size before they divide, and because adult heart cells are capable only of an increase in size and incapable of cell division, we thought it possible that heparin might inhibit cardiac hypertrophy. Consequently in studies performed for other reasons, we were able to make incidental observations of the heart weight to body weight ratios of rats treated with either saline or isoproterenol. Using this rough estimate of hypertrophy we were able to confirm as others has shown that isoproterenol causes hypertrophy. However, heparin neither decreased the heart weight to body weight ratios of the saline controls or of the rats in whom hypertrophy has been created by isoproterenol infusions.
